The present invention relates to a vehicle window position sensor. In particular, the present invention relates to an apparatus for detecting if a vehicle window is open and for providing an output signal indicative of the open or closed state of the window.
It is sometimes desirable to know whether a window in a vehicle is open or closed. For example, if the vehicle is exited and locked, a signal can be provided to alert the driver if a window is inadvertently left open.
There are known ways of detecting if a vehicle window is open and of providing an output signal indicative of the open or closed state of the window. For example, U.S. Pat. No. 4,808,894 discloses the use of a switch at the top of a door frame to indicate when a window is fully closed. U.S. Pat. No. 4,931,74 discloses the use of a slide rheostat to determine the position of a window along a window track. U.S. Pat. No. 5,410,226 discloses the use of signals indicative of motor rotation and current draw to sense an obstacle to the movement of a window along a window track. In addition, U.S. Pat. No. 5,532,560 discloses the use of a photoresistive sensor for sensing the amount of light striking a window area and, in response, controlling a Venetian blind.
The present invention is an apparatus for detecting a window open condition. The apparatus comprises a first photoelectric cell mountable to the window for providing a reference output signal independent of the window open condition. The apparatus also comprises a second photoelectric cell mountable to the window and providing a signal having a first characteristic if the window is open and a second characteristic if the window is not open. The apparatus further comprises comparison means for comparing the reference output signal with the signal from the second photoelectric cell, the comparison being indicative of the open condition of the window, and means responsive to the comparison means for indicating if the vehicle window is in the open condition.